elem.11.def.24
Similar cones and cylinders are those in which the axes and the diameters of the bases are proportional.
Ὅμοιοι κῶνοι καὶ κύλινδροί εἰσιν, ὧν οἵ τε ἄξονες καὶ αἱ διάμετροι τῶν βάσεων ἀνάλογόν εἰσιν.